


Stiletto

by Eloisa



Category: Captain America (Movies), Iron Man (Movies), Marvel Cinematic Universe, The Avengers (Marvel Movies), Thor (Movies)
Genre: Action/Adventure, BAMF Natasha Romanov, Clint Barton & Natasha Romanov Friendship, Gen, Hydra (Marvel), London, London Underground, Natasha-centric, POV Natasha Romanov, Post-Avengers (2012), Stealth Crossover, Tony Is Not Helping
Language: English
Status: Completed
Published: 2014-12-28
Updated: 2014-12-29
Packaged: 2018-03-04 01:26:31
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 3
Words: 6,459
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/2904215
Author URL: https://archiveofourown.org/users/Eloisa/pseuds/Eloisa
Summary: <blockquote class="userstuff">
              <p>Tony has a date in London to promote clean energy.  HYDRA wants to misuse his and Bruce's invention.  Natasha has to save the day.  With mild doses of the British spy network (the filmgoer version), and peppered with Tube-lore, but mostly Natasha.</p>
            </blockquote>





	1. Leviathan

Over many years Natasha had decided that the part of her job she disliked most was the shoes.  Pointed contraptions with three-inch spikes for heels: in every moment she spent standing at Tony Stark’s shoulder playing the model secretary, or smiling at a target across a crowded bar, they pinched her toes and sent pain shooting through her tendons. 

They’d proved useful once (the man’s employers never worked out what weapon had pierced his eyeball).  Other than then, she always kicked them off as soon as it was time to change from cerebral to physical work.  She’d left them scattered behind her in Paris, Los Angeles, Mexico City, Sao Paolo, Tokyo and Muscat.  Maybe they’d brought a little pleasure to whatever foolish girl found them (except the set she’d abandoned in a sewer under the Bronx), and it had always been so satisfying to present her Manolo Blahnik bills to S.H.I.E.L.D.  That was, until Tony started paying for them himself, along with the Avengers’ other equipment.  He never even checked her expenses forms before signing them off.

And now her toes were crushed against themselves again, to the tune of a string quartet playing up ahead. Royal College of Music students, genuine ones according to the MI5 intel S.H.I.E.L.D had garnered. 

“Ladies and Steve, welcome to the Mansion House,” Tony murmured, smile broad on his face as he crested the pale stone steps, waltzed through the door and strutted his way into the banqueting room in the lead. The crowd already inside, city types and industrial magnates for the most part, parted in front of him like a wheat field.

Pepper, drifting along at Tony’s right side down the thick red-and-gold carpet, rolled her eyes, but she did not answer him. Radiant in a green dress and ankle-breaking Jimmy Choos, she tucked her arm tighter into Tony’s and fired off a few swift answers to journalists’ incoming queries on Stark Industries’ finances, and added just as swift a set of queries about the balance sheet of an energy sector competitor.  Steve Rogers, striding along on Tony’s other side, just gave a bashful smile, embodying the handsome hero of wars sixty years apart in a way he could never have done had anyone actually asked him to play a role.  Natasha hovered behind them, just Natalie Rushman, the efficient assistant.  In a trouser suit and Louboutins.

She smiled at a hedge fund manager across the room, let her eyes wander past the MI5 and CIA men in the background – they knew who she was – and unselfconsciously adjusted the stray locks that brushed her dangling pearl earrings.  A passing waiter pressed a champagne glass upon her: she lifted her it to her lips.  “Test,” she breathed into the glass.

“Still reading you,” Clint answered down the earpiece built into her right earring.  Natasha exhaled.  Clint, outside on the roof, patrolling their perimeter.  Bruce, fussing with Tony’s demonstration device on the rostrum ahead, next to an atypically understated brown case that contained a set of Iron Man’s armour.  She missed Thor, as she did every time they planned for a situation indistinguishable between business conference and trap, but wishes were wind.

“Roger,” she murmured to Clint, and turned, plastering a winning smile on her face.  “Captain Rogers!”  Steve smiled down at her and let her draw him a little way from Tony to talk to the French chief of staff.

HYDRA’s rumours had many heads.  Some were started by HYDRA themselves, some started by their rivals, some started by the same idiots who had called the police with bomb scares for decades: government agencies were good at distinguishing between the real threats and the pretences, but they could never be entirely accurate.  No one could.

If HYDRA could resist bait like tonight’s, Natasha would eat her stilettos.

“My lords, ladies and gentlemen,” chief bigwig mark one said from his podium, “welcome to the London Forum of Clean Fusion. It is my pleasure to introduce this evening’s keynote speaker, Mr Tony Stark.”  Tony squeezed Pepper’s arm and smiled as he ambled away from her and onto the rostrum.

“Ladies and gentlemen,” he said, “it’s great to be here…”

Natasha let her eyes wander away from Tony and around the room again, past fluted pillars and tall windows. Of all these people, these incessant impossible people, which was the most likely to be an enemy agent? That waitress in a neat black dress and too-clean apron. The old men joking under Tony’s speech – no, they were clean: genuine financiers who believed the world was theirs. The young men scattered around the room watching Tony too closely?

“…clean energy, to me, is the absolute peak of what Stark Industries has spent the past few years creating…”

Or the ones watching Bruce more than they watched Tony? Natasha counted: five people, three men and two women, had half an ear on Tony’s speech and both their eyes firmly on Bruce’s adjustments.

“…the miniaturisation of the fusion process is as crucial to our future as increased nuclear safety…”

Steve was standing close enough to Tony to act as bodyguard if necessary. Natasha smiled at him, so sweetly that he might realise there was a problem, and drifted to her left, towards Bruce and the mechanism. Toroid-shaped, as tall as a man: its most easily sabotaged parts lay under the casing area closest to Bruce’s hands.

“…magnetic confinement geometry is advanced enough to provide a stable beam of power, easily focused into the existing power lines…”

Outside, a loud klaxon went off. Natasha froze in place. Tony stopped mid-sentence and stared at the door, then at the chief bigwig. Bruce hooked the mini reactor’s casing closed and stared at Tony.

Chief bigwig was staring at his phone. Steve cleared his throat. “Is something the matter? The alarm?” He gestured in the direction of the sound.

The man’s face froze in position. “Everything’s fine, Captain Rogers. I just need to step outside for one moment.” He slid the phone back into his pocket and backed off a pace.

Natasha frowned. ‘Chief bigwig’, her memory belatedly informed her, was the governor of the Bank of England. The Bank, which was in the direction of that alarm bell. Steve must have made the same connection. He hurried past the governor out of the Mansion House, towards the alarm.

Tony cleared his throat. “In short, folks, before too long you’ll see a version of this very fusion generator in every home and business on the planet. Questions?”

One of the BBC journalists captured the roving microphone already in motion round the floor. “Fusion power in every home and business on the planet would mean a lot of nuclear material that can be stolen by terrorists. What measures can we take to prevent this?”

“Clean fusion,” Tony answered. “Clean. As in the opposite of dirty. The reactors split non-radioactive chemicals into radioactive isotopes, a reaction that is shut off if the casing is opened in any way. There’s nothing to steal.” He pointed to a man wearing an SAPA badge. “Your question?”

“Mr Stark, how would you assess claims that development of this technology is a route to weapons development via the back door?”

Tony smiled, as if to a child, or as if he were a child. “An interesting theory and one to which I have given my full attention, for the ninety seconds or so it took me to route round the convertors and institute a feedback via the ionised hydrogen byproducts to prevent any focus of the beam when it hasn’t anywhere to go. All very basic.” He pointed to the next journalist in line, a blonde woman with a Fox News lanyard. “Next?”

“Mr Stark, I wonder if you could comment on the high probability of HYDRA agents attacking your installations in order to pursue weaponisation of your invention –”

The blonde dropped her handbag, raised a semi-automatic and fired point-blank at Bruce’s head.

But that didn’t work, and it never worked, and Natasha backpedalled as the Hulk, roaring in anger, swelled up to his full height and smashed a fist down at the blonde.

She folded into a crumpled pile, something no longer human. Behind, another four figures drew guns – two men, the quartet’s viola player (so much for intel) and a journalist, and two women, a business type and a waitress. The violist’s gun hand hesitated for half a second, and then stopped moving towards Tony and shifted towards Natasha. She drew her own gun and shot him before he could level on her.

Around, all was chaos. Tony’s armour cascading onto him, curtains cascading to the floor, people screaming, the Hulk roaring. Natasha turned on her pointed heel towards the businesswoman she’d seen draw a gun, but the woman folded to the ground, with two bullet holes through her head, before Natasha could act. Instead she fired on the male journalist now reaching for the fusion reactor.

The Hulk’s massive foot slammed into the floor straight between Natasha and her target, and the bullet glanced off his hide into the closest wall. Natasha swore under her breath – she’d always tried not to swear too loudly, as for all her multilingualism, she couldn’t stop herself from cursing in Russian – and dodged Hulk’s other foot.

She came right up against one of the respectable older financiers. “I’m sorry!” the man gasped. She nodded to him and tried to sidestep.

His hand gripped her gun hand’s wrist. “I’m sorry,” he whispered, something more than menacing, and his free hand went to his so-expensive tweeds’ pocket. Before Natasha could throw him off, though, another gunshot from off to the right bit into his head. His hand went limp and he collapsed.

Natasha ran round Hulk’s flailing fury, calculating. Tony and Bruce had no guns. Steve was armed, but he’d headed for the bank several minutes earlier. The MI5 and CIA crew were all over on the far sides of the room, in the wrong place to have shot that financier.

She stopped just under Hulk’s elbow. Tony, armour on and thrusters at full power, was pushing him backwards away from Pepper and the Lord Mayor (Pepper was the more composed of the two, Natasha noted). Nothing else. The toroidal fusion generator, still on its wheeled trolley, was gone.

Natasha looked round. Back door – _there_ , right ahead, with the male agent vanishing through it, and a clattering decrescendo from the toroid’s trolley. She started for the door.

“Nat, _wait_!” Tony yelled.

No time to wait. She rolled under the Hulk’s swinging fist, vaulted a flying pot plant, ducked under the end of the seven-foot curtain pole Hulk had grabbed with which to prise off Tony’s armour, and hit the door. Through the porch, to the street. A backstreet.

She kicked off her Louboutins and pulled a pair of rolled-up slim pumps from her pocket. Right or left? Right was a brightly-lit crossroads, five streets meeting at a point, with the Bank of England at its head. Left was a much dimmer straight street pierced by two crossroads. Down the end, a man-shaped shadow was receding towards the river. Natasha yanked on her fresh shoes and ran to the left.

An old church reared up to her left, then a long office block, opposite a building site. The man ahead had a sizeable lead: by the time Natasha was halfway down the office building, he had vanished over the brow of the hill ahead. Short hill, she knew, just a slope down to Upper Thames Street and then to the river: ahead there was a stairway at the riverfront, next to an old pub bricked into the bridge itself, where a boat could tether. Natasha pushed her earring round her face, as close to her lips as she could get it. “Yours, Hawkeye.”

“On it.” One _thunk_ of an arrow, and outlined in lamplight she saw Clint swing on a wire across Cannon Street, down onto the office block fronting the station. He landed and fired again, archer as icon, and swung away out of sight.

Perching on the station’s river-front towers wouldn’t do them any good if the agent had moored a boat under the railway bridge. Natasha slowed down a fraction. That was a HYDRA agent, sure, or he wouldn’t be running away, but a man pushing something as tall again as himself? No.

She stopped at the junction with Cannon Street. From here, the hill top, she could see the river ahead, glittering under evening lights. _No_ – the river was a blind. She glanced right, then left – and, yes, down the street to the left, trotting past the station’s deserted steps and padlocked gratings, was another male figure, running as well as he could when he was towing a trolley behind him. A trolley carrying something the approximate size of Tony’s fusion generator.

Natasha took off after him. As she ran past the station’s frontage on one side, and a string of closed shops and banks on the other, she heard a rattle of gunfire from the river beyond, and a cry of pain. That wasn’t Clint. She kept going.

“Natasha?” That _was_ Clint, down her earpiece. “If that guy had Tony’s parcel, it’s at the bottom of the Thames –”

“He didn’t. He was the decoy. Go east along the river-front. I’m trailing.”

Clint hesitated, for too long. “I might have to leave you hanging.”

“Have you been shot?”

“Glancing hit. I just need to sit down for a bit.”

Natasha swore, loud enough for Clint to hear her, and kept running with one ear fiddling at her earpiece. “Steve?”

“Still me,” Clint answered. “Bust your radio?”

He would have told her if he was seriously injured. She couldn’t say much more to him. “Call Steve, and tell him where I’m going. I’ll assume Tony’s still busy with Bruce.”

“Where are you going?”

Ahead, Natasha’s target veered across the street to the right, in complete safety as there was no traffic passing. Too little traffic for a city centre, even in a financial district street outside of financial district hours: the police cordon around the Bank of England keeping buses and taxis away? “He’s heading towards London Bridge.”

“Got you.” Clint half-laughed. “If he goes onto the bridge I can hit him from here.”

“Don’t –” _Don’t fall off the tower_ , she wanted to say, _you must be losing too much blood to stay hooked on to it with one leg_ , but instead she said, “Don’t rule out a boat moored under one of the bridges.”

“If he gets onto a boat and goes either upriver or downriver, I’ll be able to hit him.”

She left it at that. The agent had vanished down the next street on the right, in the bridge’s direction. She hit the corner and looked ahead, hoping to see him, seeing a fraction of movement. _Not_ into another side street, or onto the bridge: into an office building, tall and white.

Natasha crossed the street and ran inside after him, guns up. No need to talk her way past the security guard, for the guard lay dead in the lobby, and a door was swinging in the background. Moving more cautiously now, Natasha stepped over the dead guard and padded for the door.

It opened onto a stairwell. Natasha glanced upwards. The generator wasn’t over-light, and bouncing a trolley down stairs was far easier than shoving it up them. With her back to the wall, Natasha inched downwards gun-barrel first. No one was waiting at the bottom, hidden under the staircase: just a single door faced her. She slid through and into a dim basement.

A hatch in the floor in front of her gaped open.  Down below, she could hear the faint crunch of boots, heading away.

Natasha ran for the hatch and dropped through it feet first and guns up.  As her shoes touched the iron spiral staircase beneath, all the lights went out.  She glanced upwards just in time to see the hatch swinging closed above her head.


	2. Hades

**Summary for the Chapter:**

> A HYDRA agent and an abandoned tube station - not Natasha's favourite combination.

In the dark. Alone. _Great._

Natasha closed her eyes for three seconds and opened them again. _Almost_ no light: faint glimmers trickled to her from corridors far away. It was enough. She stashed one gun and felt for the staircase, exploring its dimensions, and then with one hand held above her head, she climbed the few steps to the top till her fingertips touched the entry hatch. She pushed, first gently, then hard. It didn’t budge. Locked, or weighted down. She must have been trailed by another agent, who’d locked her in.

 _Of course, it couldn’t have been Steve or Tony or Bruce who got stuck down here, could it? Any of them could get this damnable lid open._ Her own fault, though, for failing to consider the consequences. At least her enemy above had preferred to seal her in rather than kill her.

Logic said that either the agent who’d run down here was to be sacrificed, or said agent knew there was a way out, and had enough of a lead on Natasha – on ground unfamiliar to her – that the HYDRA team counted his escape almost certain.

Natasha descended the stairs one at a time till they opened onto a concrete floor, then inhaled deeply and held her breath, listening, feeling. A vague cool breeze on her left cheek. Mice or rats squeaking faintly in the middle distance. That meant the agent was long gone. Too far away to hear her.

She touched her earring. “Clint. Are you there?”

“You sound fuzzy.” _He_ sounded fuzzy and far-away, but he was there, and just hearing his voice made Natasha feel less isolated. Dangerous thought. She _was_ isolated, down here. “What’s happened?”

“I’m stuck in a basement.” If the agent was gone… Natasha slid her pen torch from her bra and flicked it on.

1940s posters faced her. ‘We Can Do It!’ one of them shouted¸ and ‘Careless Talk Costs Lives’. Iron bunk beds with rotting mattresses lined the back wall: a back wall with a rounded, tiled roof that looked oddly familiar.

“This was an air raid shelter.” Natasha peered left and right. Right, the room ended at a bare concrete wall: left, the room – eight feet wide or so – continued for twenty or thirty feet before narrowing into a passage just wide enough for one person to pass another. Always with the rounded tunnel-like architecture. “I think this was once an Underground station.”

She heard Clint click around in a database. “King William Street station’s two streets away from me, close to your exact position.”

She turned off the torch to let her eyes readjust to near-zero light. “I don’t care what it’s called: I’m stuck in it. The hatch won’t move.”

“When Bruce stops flipping out we’ll have him or Tony fix that.”

“You fill me with confidence.” One hand out in front of herself, Natasha tiptoed across the room in the direction of the exit passage. Her hand encountered the iron bedframes a couple of times, but eventually she found the passage mouth. 

It was almost – _almost_ – pitch dark. Natasha walked slowly, setting each foot down in a careful deliberate movement, and was rewarded when her foot went further than expected. She fumbled left, found the wall, and touched the staircase’s handrail.

“Steve’s coming to let you out,” Clint said down Natasha’s ear. “Finished scaring HYDRA off the bank. They were trying to penetrate the gold vault… Nat.”

Her questing right toe found the stair bottom. She could see now, just: shadows and shapes. Enough to jog on into the dark. “What?” 

“If someone wanted gold, why not go for the American stockpile? It’s far bigger.”

“Fort Knox is a nightmare to penetrate, and the Federal Reserve is two blocks down from Stark Towers.” The earring was jiggling around, shaking loose its earpiece. Still jogging, Natasha pulled out her spare headset from her bra’s underwiring, slid it on and clipped the earpiece to that instead. “Can you still hear me?”

“Yes. And it doesn’t make sense either way.”

She paused at a crossway in the tunnel. Still nothing but the faint smell of dirt, decay and mouse. “Mmm?”

“Half the world knows Tony’s here. They must have expected us to step in. It’s what we do.”

That distant rumble and rattle again. Natasha pressed herself into the wall. Unused, unusable tunnels. “Exactly what I was thinking. No one wanted gold at all.” Another noise, behind the rumbling, almost coated by it. Almost, but not quite. “Quiet, Clint.”

Upsetting Bruce, and taking him and Tony out of the equation, even for a few minutes. Drawing Steve off to firefight at an incident that ultimately didn’t matter. Neutralising Clint by moving underground – for shooting him was a bonus upon which they couldn’t have counted. That left Natasha. They had planned that it was her who would follow.

Follow a man who either had a technological marvel in his hands – if Tony were to be believed when he spoke of fail-safes – or, if Tony had been exaggerating the reactor’s safety, a nuclear bomb. No, she definitely didn't have time to wait for Steve.

The concrete beneath her feet gave way to dirt. Her left foot squelched into a patch of mud. Rumble and rattle, ahead. _An old tube station._ An old tube station that was, maybe, still connected to the network. The agent’s way out?

Natasha backed up twenty feet or so round one of the cross-passages and whispered into her earpiece, “Clint – check if King Whoever Street station has an exit into the main Tube network.”

For a moment she thought he hadn’t heard her, too deep underground, but then he replied in a faint buzz, “King William. And it used to have one – it was filled in a way back. There’s a few vents you might still be able to get through, though.”

In other words, the agent could have removed one of those vents’ hatching as an escape route – or could be planning to ambush Natasha in a dark dead end and then get his buddy upstairs to let him out, reactor intact. _Great_.

One pistol stashed in her pocket and the other raised and ready, she returned to the cross-way and tiptoed along into the unknown. Potential bomb notwithstanding, a decent segment of her wanted to abandon Tony’s contraption and find one of the potential escape routes Clint had mentioned: but if the agent hadn’t prepared an escape route, she wouldn’t be able to get out that way anyway, for she had nothing with which to force a vent open – not even the heel of a ridiculously pointed shoe.

Natasha stopped, concentrating on the faint breeze on her face. Another tiny noise drifted to her, neither mouse nor train, in the opposite direction from the breeze. Natasha crept down the corridor away from the breeze, towards the sound, and the man.

After another dozen yards the air’s breath on the back of her head cut out. The faint noises were becoming even fainter.

Natasha stopped in mid-stride. Ahead was light. Not much: a bare glimmer, a mere shift in shades of near-black. But definitely light.

Placing her feet as quietly as she could, she headed towards the glimmer. The ground tilted downwards under her feet, and the ceiling was low, where a second storey had been built as a mezzanine. She crept to an identifiable doorway, with a serving hatch built into one wall alongside. Here, the light was stronger: enough for her to see a single set of footsteps and a set of wheel tracks in sixty years’ accumulated muck. Walking in the footsteps, she continued, past what looked like door-less lavatory cubicles, to a tunnel mouth ribbed with steel. The floor was becoming damper, and the downward tilt more pronounced.

A leftward turn ahead. A light, clear and bright, past the turn. Natasha pressed her back to the filthy wall and held a pistol up beside her head, preparing to round the corner with it raised.

A gun’s muzzle pressed into the back of her neck.


	3. Phoenix

**Summary for the Chapter:**

> Natasha confronts the HYDRA agent, and hopes Tony has been too clever for them both.

Over many years Natasha had developed a keen sense of what to do when threatened. Boot to attacker’s instep and forearm to wrist – knocking the gun upwards – would have been an option. She stayed motionless instead.

“Drop your gun and walk on,” a man’s low voice said from behind her. She complied.

Beyond was the end of a tunnel, arch-roofed and coated in broken tiling. A single bulb in a workman’s cage was hooked to a bar in the ceiling. Floodwater ran across the floor, halfway along the tunnel where its tilt became most pronounced.  Tony’s clean fusion reactor, still on its trolley, sat in the middle of the room, just before the water. Mice fussed by the wall, at the water’s edge, near a crack in the brickwork. The tunnel ended a few yards ahead at a concrete bulkhead sporting a single steel door. A tiny fraction of the tension in Natasha’s chest dissipated.

“‘Magnetic confinement geometry’,” the agent said, at Natasha’s back. “Don’t you like Stark’s phrasing?” The agent prodded Natasha in the back with his gun. Hands spread to her sides, Natasha turned round.

The man was one of the youngsters who’d been staring too hard at Tony during the speech, the one who’d worn a black shirt and pale tie beneath his charcoal suit. He’d lost the tie and suit jacket in the intervening period. In the street, she wouldn’t have looked at him twice: neither ugly nor handsome, neither tall nor short, brown hair and tanned white skin. He could have blended into almost any scene – if he’d tried a little harder than he had at the press conference.

When Natasha didn’t speak, the agent pointed to the toroid. “Stark didn’t mention it needs a tiny kick-starter of chromium. That information wasn’t in our reports either: luckily, London Underground dust contains a relatively high concentration.”

He gestured Natasha away from the generator with a tiny movement from his gun. She complied. “You heard the speech. Tony added a fail-safe. It can’t fire off raw power with nowhere to go like some fictional death ray, or just explode like a bomb: it needs an outlet.” She glanced down at the generator’s tip. Tony or Bruce had stuck a standard British power socket, three plug prongs, on the end. So that was why Pepper had been carting around a lava lamp.

The agent’s free hand pulled an unmarked mains-to-USB plug from his pocket. “So let’s make it think it’s plugged into something.” Without looking away from Natasha, or moving his gun’s barrel from her torso, he bent and slotted the plug into the socket. “If I’m not mistaken, the amount of power generated by this little monster should blow the plug to smithereens – and everything around it.” He smiled at her, not pleasantly.

“If it has that kind of power, and if you fire it in here, you’ll kill yourself too.”

“A hydra has many heads.” He flipped open a hatch on top of the toroid and, still staring at Natasha, bent to a tiny box beside the trolley. The box squeaked as he lifted it. “The mice on the London Underground are fascinating little creatures,” the agent continued. “Some people say they’re a separate species from your average wild mouse, they’ve been inbreeding for so long. That probably isn’t true, but their fur is caked with dust from the trains.” He laid the box on top of the toroid, reached inside – still without looking – and pulled out a mouse by its tail. It squeaked frantically, squirming to escape. Slowly, the agent dropped the mouse into the open hatch, and slammed it shut before the little creature could clamber out.

“Now,” the agent continued, “if you’ll kindly wade into that water and stand between the machine and that patch of concrete, we’ll see if its beam has enough power to blast through you and it at the same time. I don’t plan on dying right now, you see.”

Natasha was almost certain that that was a lie.

The agent gestured with his pistol. Natasha didn’t move. “Be shot or be blasted into smithereens by a concentrated burst from a fusion reactor: that’s not a good choice,” she said.

“Do as I say!” the agent barked, shaking his gun. “I want to watch you drown in plasma before I die.”

 _Drowning, drowning_. The river? It was less than a hundred yards away from the door she’d used to enter the office block over the station. All this flooding underfoot: maybe that bulkhead led to an old tunnel under the river itself.

Could the river water sweep from a breach in its banks or bed, through the abandoned station and through those vents Clint had mentioned, into the main Tube network? If so, the whole city’s foundations would destabilise.

Natasha stared at the toroid. If Tony had any sense, his fail-safe would be more elaborate than an absence of mouse-dust. She backed away from the agent, edging towards the water, but with her weight on her left foot, ready to spring to one side at the next opportunity. “Good, good,” the agent said, and he laid his hand on the switch. “Now. Let us together welcome in a new world. Hail HYDRA.”

Natasha’s hand snapped up with her second pistol in it. She fired. The agent collapsed forwards, not dead, maybe dying. He fired his own pistol. The shot missed Natasha by a foot.

But his left hand, outstretched, slammed the generator switch home as he fell. Natasha ducked out of the way, pointless though it seemed.

White light flooded the tunnel mouth. Natasha heard a scream, frightfully loud, frightfully close. Maybe it was the agent: maybe it was herself.

She took a deep breath and threw herself face down into the water. The screaming peaked – _not_ her, definitely – and the light penetrating both water and her screwed-shut lids changed.

Still underwater, she cracked her eyes open. Rainbows – a rainbow prism split the dank air, penetrating everything it touched: shining, glittering, impossible to comprehend. It was no longer blindingly bright, though. Natasha knelt up, head above water, and opened her eyes.

The fusion generator was a twisted ruin, blasted open from within by its own power. The agent lay on the ground, a black shape in a world of light, very dead. Standing over him was a man, clad in gold armour and helmet, with a huge sword held beneath his clasped hands. As Natasha got her feet underneath herself, he turned and stared down at her. Massively tall, with black skin and a close black beard, it felt as if he looked straight through her, and knew her worst excesses better than she did herself.

“Lady Natasha,” he said, more a statement than a question, and he held out one hand and drew her to her feet. “I am honoured.”

“L-likewise.” The rainbows were whirling around his feet, she realised, as if they knew him. She gestured to them. “Is this… normal?”

He smiled. “Within parameters. We have each restored something to the other.” He stepped back, wrapped both hands round his sword hilt and drove it into the floor just shy of the water. Light flared again, upwards this time. Natasha felt for her headset, clicked the buttons, but nothing happened. She didn’t know what hurt worse – that she couldn’t raise Clint and Steve, or that she had no right to try.

The rainbow brightened. Natasha threw an arm across her eyes, shielding them. Half-heard, half felt, the rainbow _sang_ a deep tuneful note – and its light winked out.

Natasha lowered her arm. The electric light was still on overhead. Thor stood beneath it, light glinting off his armour just as it did off the water. A dazed-looking mouse ran down his boot and vanished into the crack in the wall.

“Thor?” She took a quick step towards him. He stared down at her, a smile growing on his lips – but the smile froze, as did Natasha, as a stranger’s throat cleared from the tunnel turn.

“Natalia Romanova, I presume?” the newcomer said.

“Natasha Romanoff.” Natasha peered at the woman in the tunnel mouth. She had shed her waitress’s apron and hairnet. The Steyr M pistol in her right hand, currently lowered, was slim enough that she might have had it hidden in a pocket under the apron during the reception, before she'd taken it out to shoot the HYDRA agent threatening Natasha. “You're MI5?”

“MI6. Helen Strood.” She smiled, a social marionette. “I never knew your parents, but I knew of them, of course.”

“As did I.”

“Well.” Strood looked faintly embarrassed for a moment. Her eyes flicked to Thor, and to the mud on the floor. “When you threw away your shoes I realised who you were.” She revealed a bundle in her left hand – Natasha’s sparkling Louboutins – and passed them over. Natasha let them fall into the mud.

“Why are you here?” she said. “MI6 has no remit in Britain.”

“MI6 has a remit over HYDRA. We knew they would attack the conference. Doctor Banner told us about the feedback loop: my role is to evaluate whatever was left.” She craned her neck at the agent’s corpse. “This will be very useful.”

“Bruce told you.” A few things clicked together: Bruce’s nerves, Tony’s relaxation. They hadn’t brought the real prototype. They’d brought something that would sabotage itself both immediately and spectacularly if they weren’t around to stop it.

And they hadn’t told their own team-mates.

She’d kick them both to shreds as soon as she got above ground.

Strood glanced at the ceiling. “I’m about to escort two of my colleagues in here to retrieve our late friend. I’m afraid I’ll have to ask you both to leave.”

“With pleasure.” Natasha stepped over her Louboutins and stalked towards the door.

Strood cocked her head at her. “You’ve forgotten your shoes again.”

“I hate the things. Do you want them? Have them.”

A ray of genuine pleasure passed over Strood’s ascetic face. “Can I? Really?”

Natasha shrugged. “They’re yours. I’m –” She calculated. “A British size seven.”

“I’m a seven and a half, but I wear heels half a size too small.” She picked up the shoes and tucked their heels through her belt. “Thank you.” Beaming, she nodded to Natasha and Thor, and hurried out. Natasha heard her calling to another British-accented intelligence officer down the hallway.

Thor looked down at Natasha. “I will pass over that particular example of Midgardian etiquette.” He swept her into a tight hug, heedless of her soaking clothes. “It is _good_ to see you again.”

“And you.” Tears pricked at her eyes, no matter how she told them to stop. “I think I missed you more than I realised.”

He dropped a brotherly kiss onto her head and released her. “You’re looking well.”

“I don’t feel it. Tony and Bruce just screwed me over and I didn’t even notice.”

“I am sure they had the best of intentions.” Natasha bit her lip. Intentions? She’d nearly been killed, Clint had been shot, and –

And thanks to their little secrets, she’d been the first to welcome Thor back to their coterie.

She hooked his arm, brushing the familiar bulk of Mjolnir at his side, and walked him back through the tunnels towards the staircase, past Strood and two of her colleagues (she half-recognised them, as if she’d seen them in some film or other). “Do you think they intended its power to feed back into the Bifröst?” she said.

“Doctor Banner and Tony Stark? I think so. It would have been simple for Jane or Doctor Selvig to calculate the power needed to restore the Bifröst. More power than my father can summon: that much I know.” He smiled, reflective. “I see Asgard and Midgard have more to learn from each other than I had suspected.”

“If they did all this to get you back, I’ll forgive them. Maybe not if it was a happy accident.” He laughed.

Strood and her friends had levered up the hatch at the stairhead: Natasha let Thor lead the way up the ladder – maybe Frigga had been working on his etiquette – but when they were both upstairs, she stepped over the pool of blood that Strood had extracted from the HYDRA agent who had remained above ground, and headed past Thor and out into the street. She stood for a moment staring at the Thames, no more than fifty feet away with its ripples twinkling in street lights, flowing out of the city heedless of time or events. Maybe it was better to be a river - not to know or care about the uses to which it were put.

Thor touched her arm, and she turned and walked with him back north to the crossroads. They were no more than two hundred yards from the Mansion House. Stretching away to the west, Cannon Street was still almost empty: a few bar signs and takeaway lights illuminated their path. One of the stores on the far side of the street had hollowed out the section of wall below its window display. A rough-cut stone bigger than a man’s head sat in the hollow, protected by glazing and grating, lit from below as if it were a museum exhibit.

Thor trotted across the street and bent to peer at the stone, his face breaking into a broad smile. “Something amusing?” Natasha said.

“My father set this rock here thousands of years ago. I am glad to see it. It carries a blessing.” He straightened up and grinned, if it were possible, even wider. “I say we gather our friends and drink to comradeship.”

She glanced past his shoulder. Steve and Bruce were standing a few feet away, the one with scorch-marks on his outfit and the other in partial rags. Steve was watching Thor and Natasha’s approach, and Bruce was looking back at Tony helping Clint limp towards them. In the background, a pair of bar signs glinted their welcome. It was best to enjoy the time she had with her friends as much as she could, for it would not, could not last. “When Clint’s stopped bleeding, I could go with that.”

*

She saw Strood once more, two years later, during a HYDRA raid on the CBN’s Abuja headquarters. As soon as Natasha fought her way downstairs she found Strood outside the entrance to the main vault, with six bodies arrayed before her like a hunter’s prizes. Lacking other options, Natasha straightened the Louboutins on Strood’s dead feet, and reloaded her gun and walked on into the future.

**Notes for the Chapter:**

> King William Street station really exists. Some photos of the corridors Natasha searched are online [here](http://www.subbrit.org.uk/sb-sites/sites/k/king_william_street_station/index.shtml). The tunnel flooding is actually due to condensation collecting in the steep gradient south of the station, but the point where the HYDRA agent threatened to blow up the tunnel is indeed a few yards from the Thames. The station is still accessible through the basement of Regis House, which is the entrance Natasha used, and if one had heavy equipment one could dig into it from London Bridge Underground station, but it is no longer open for guided tours due to naked electricity conduits.
> 
> The rock Thor greets at the end is the London Stone. It is over a thousand years old, and very probably two thousand: a not-so-old legend states that if it leaves London the city will fall. I decided Odin had something to do with it, as he clearly could have a connection to the similar legend about the ravens at the Tower of London.
> 
> I have always assumed the James Bond books and movies exist in the same world as S.H.I.E.L.D., if only because the crossover potential is so vast. In particular, the first fictional "Romanova" who springs to my mind when I hear the name is never Natasha, but the leading woman of _From Russia With Love_.


End file.
